In another approach that has become known through the applicant, the plastic preform is, to start with, evenly heated in an oven and is subsequently tempered differently, for example “cooled”, in certain places in a targeted manner. The term “cooling” is here not necessarily understood to mean cooling at a low temperature, but rather a targeted and partial tempering of the preforms at a temperature that is below the temperature the preforms have after having been heated in the oven. This means that the partial tempering is carried out at a temperature that is substantially cooler or lower compared to the temperature of the preforms after having been heated in the oven. In this method, an intermediate module is provided downstream of the heating oven, which partially tempers the plastic preforms by means of embossing plates. More specifically, in the method known from the applicant, the plastic preform is inserted between two embossing plates along the longitudinal direction thereof or vertically. This vertical movement can be achieved via a continuous groove cam. Subsequently, the embossing plates are actuated via a drive device for each station and, if needed, the plastic preform is rotated.
With this approach, different problems arise. To ensure that the plastic preform can be transferred to the apparatus for tempering by a further transport device such as for example a reduction star wheel, the plastic preform is held by this further transport device and a mandrel or, more specifically, a holding mandrel of the actual tempering apparatus is moved into the mouth of the plastic preform. In this way, vertical forces occur during the insertion process, which however are frequently too high for the clamp of the input star wheel.
In order to absorb these vertically occurring forces, stationary support modules are required which can lead to a subsequent twisting of the plastic preform, so that the orientation process of the plastic preform may become incorrect, because a rotary position of the plastic preform is usually detected prior to its input into the station. However, the orientation process itself will only be carried out within the station via a stepper motor. This means, should the preform be accidentally twisted again on its way between the camera inspection and the orientation, the orientation process would be incorrect and the correct rotary position would not be reached. The orientation of the plastic preform or the rotary position thereof is of high significance for the application of the temperature profile onto the required places in a targeted manner. Apart from that, for moving the plastic preform between the embossing plates, the high vertical lift requires a large, complex and expensive lifting cam in the prior art, which causes high loads on the traversing slide. Apart from that, process time is lost as a result of this traversing movement.
A further problem arises partially during the opening and closing movement of the embossing plates (referred to below as contacting device). To this end, pneumatic cylinders are used in the applicant's internal art. Pneumatic cylinders do not ensure a constant and consistent switching time, so that as a rule, a certain scattering occurs between the different treatment stations. The different embossing times or contacting times, in which the embossing plates touch the outer walls of the plastic preforms, reduce the quality of the moulded bottles.
The present invention is therefore based on the aspect of designing the manufacturing process for such non-circular containers in a simpler way. Apart from that, also the possibility is to be provided to reduce deviations between individual treatment stations.